When trying to use an invalid symbol name when defining a function, the error message thrown is a confusing and wrong one. The error message is "RuntimeException Unmatched delimiter: ) clojure.lang.Util.runtimeException (Util.java:219)", which unfortunately is the only message seen in nrepled emacs.

when you type (defn 45fn [] nil) and hit enter, the inputstream flushes and "(defn 45fn [] nil)" is made available to the reader, the reader reads up to 45fn, throws an error back to the main repl loop, which prints out the error, then calls read, which still has the unread parts available to it "[] nil)"

changing this behavior would require significant changes to clojure's repl.